pfSense build

I've never used pfSense and unfortunately I don't have a spare computer to experiment with. I want to build a machine using the Asrock AD2550R/U3S3. I have a 50Mbit down connection and I want to use various plugins such as built in virus scanning, web caching, and probably others that I'll find once I build.

Is the Intel Atom D2550 that is soldered on the board powerful enough for this? How much RAM would you suggest? Should I install the OS on the same drive as the web caching drive or use a USB stick for the OS?

Thanks for the help

To be perfectly honest, I've never really been a fan of using crummy atoms for pfsense. They work, just kinda "meh". I've used this board on multiple occasions and its perfect for the job.

http://www.newegg.com/Product/Product.aspx?Item=N82E16813138412&cm_re=a4_biostar-_-13-138-412-_-Product

Its dirt cheap, more that fast enough, has absolutly no issues with pfsense. Also it supports AES instructions which alot of cheap intel cpus do not. Also has a tdp of 15 watts :)